A visible light responsive photocatalytic material, its preparation, and its application in photocatalytic degradation of new pollutants

Abstract

The present invention discloses a visible light responsive photocatalytic material, its preparation and its application in the photocatalytic degradation of new pollutants. It is prepared by introducing nano zero-valent iron (nZVI) into carbon-doped g-C3N4 material (GCN-A) modified with graphene oxide (GO). The new material developed by the present invention is responsive to visible light and can use sunlight, a clean energy source, for photocatalysis. The new pollutants involved mainly include DEET, fluoroquinolones and pathogenic bacteria (MS2 bacteriophage). This patent modifies g-C3N4 by doping with nano zero-valent iron, etc., to improve the efficiency of photogenerated electron-hole separation, thereby improving its photocatalytic performance; at the same time, the photocatalytic material is attached to the film to form a photocatalytic film, so that the new material can be used in the field of water environment remediation and water treatment engineering.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalytic materials, and in particular relates to a visible light responsive photocatalytic material, its preparation method and its application in the photocatalytic degradation of new pollutants. Background Art

[0002] The novel metal-free photocatalyst graphitic carbon nitride (g-C3N4) has attracted considerable attention due to its suitable band gap (2.7 eV), excellent visible light activity, chemical stability, low cost, readily available raw materials, and environmentally friendly synthesis. However, its widespread use in practical applications is hampered by its high recombination rate of photogenerated electrons and holes, a wide band gap, and the fact that most laboratory-synthesized g-C3N4 and its modified materials are in powder form, making them difficult to recycle and reuse.

[0003] Emerging contaminants (ECs) are newly discovered or concerning pollutants that pose a risk to the ecological environment or human health, are not yet included in regulatory management, or are insufficiently managed by existing management measures to effectively prevent and control risks. Emerging contaminants can generally be categorized as persistent organic pollutants, endocrine disruptors, antibiotics, and microplastics. DEET and fluoroquinolone antibiotics, as typical emerging contaminants, are frequently detected in aquatic environments. The efficient removal of these contaminants remains a research hotspot and a challenge.

[0004] Chinese patent 202010081377.X discloses a graphene oxide-modified carbon-doped g-C3N4 material, which is loaded onto a glass fiber felt for the photocatalytic degradation of organic matter and ammonia nitrogen in slightly polluted water. However, these materials still suffer from issues such as relatively low visible light utilization and a complex loading process. Summary of the Invention

[0005] The purpose of the present invention is to provide a visible light responsive photocatalytic material.

[0006] The visible light responsive photocatalytic material provided by the present invention is prepared by introducing nano-zero-valent iron (nZVI) into a carbon-doped g-C3N4 material (GCN-A) modified with graphene oxide, and is expressed as n% IGCN, wherein n% represents the mass percentage of nZVI to GCN-A, n=0-15, the endpoint 0 is not desirable, and n can specifically be 7.5-15, 7.5-12.5, 5, 7.5, 10, 12.5 or 15, preferably 10.

[0007] The visible light responsive photocatalytic material provided by the present invention is prepared by a method comprising the following steps:

[0008] Nitrogen was first introduced into the water to remove dissolved oxygen in the water, and then graphene oxide-modified carbon-doped g-C3N4 material (GCN-A) and nano-zero-valent iron (nZVI) were dispersed in the water and ultrasonically treated to obtain a catalyst suspension, n% IGCN.

[0009] The mass percentage of nZVI and GCN-A is n%, n=0-15, the endpoint 0 is not desirable, and n can specifically be 7.5-15, 7.5-12.5, 5, 7.5, 10, 12.5 or 15, preferably 10.

[0010] The concentration of the catalyst in the obtained catalyst suspension may be 0.1-1 mg / mL, specifically 0.5 mg / mL.

[0011] The graphene oxide-modified carbon-doped g-C3N4 material (GCN-A) was prepared according to the method described in Chinese Patent No. 202010081377.X, and the specific operation was as follows:

[0012] 1) Using melamine, cyanuric acid, barbituric acid and GO dispersion as precursors, an anhydrous organic solvent is added thereto to form a suspension;

[0013] 2) subjecting the suspension to ultrasonic treatment and stirring;

[0014] 3) drying the stirred suspension to obtain an off-white solid;

[0015] 4) calcining the obtained off-white solid, and collecting the solid product after cooling to obtain a graphene oxide-modified carbon-doped g-C3N4 material, that is, a visible light responsive photocatalytic material.

[0016] In step 1) of the above method, the mass concentration of the graphene oxide (GO) dispersion is 5 mg / mL, and it is a product of Nanjing Xianfeng Nanotechnology Co., Ltd.

[0017] The ratio of melamine, cyanuric acid, barbituric acid and GO dispersion can be: 2g:1.93g:0.07g:4-40mL; specifically: 2g:1.93g:0.07g:10-40mL, more specifically: 2g:1.93g:0.07g:30mL;

[0018] The anhydrous organic solvent may specifically be anhydrous ethanol;

[0019] In step 2) of the above method, the ultrasonic treatment conditions may be: ultrasonic treatment at room temperature for 2-4 hours (KQ100 V, 37 kHz), specifically for 3 hours;

[0020] The stirring conditions may be: stirring at 350 r / min for 3 h;

[0021] In step 3) of the above method, the drying temperature may be 60-80°C, specifically 70°C;

[0022] In step 4) of the above method, the calcination may be carried out in a muffle furnace;

[0023] The calcination conditions are: heating to 550-600° C. (specifically 550° C.) at a rate of 1.5-15° C. / min (specifically 2.3° C. / min), and maintaining for 2-4 hours (specifically 4 hours);

[0024] The above method may further comprise the operation of grinding the collected solid product into powder.

[0025] The present invention also provides a membrane-supported visible light responsive photocatalytic material, which is prepared by loading the catalyst suspension onto a membrane.

[0026] The specific operation is as follows: 1) nitrogen is introduced into water to remove dissolved oxygen in the water, and the carbon-doped g-C3N4 material GCN-A modified by graphene oxide and nano zero-valent iron nZVI are dispersed in water, and ultrasonic treatment is performed to obtain a catalyst suspension, n% IGCN,

[0027] 2) The obtained catalyst suspension is vacuum filtered on a membrane to obtain the catalyst.

[0028] Wherein, the mass percentage of nZVI and GCN-A is n%, n=0-15, the endpoint 0 is not desirable, and n can be specifically 7.5-15, 7.5-12.5, 5, 7.5, 10, 12.5 or 15, preferably 10;

[0029] The mass concentration of the catalyst suspension can be 0.1-1 mg / mL, specifically 0.5 mg / mL;

[0030] The membrane can specifically be a cellulose acetate membrane, a polyvinylidene fluoride (PVDF) membrane, or a polyacrylonitrile (PAN) membrane;

[0031] The pressure of the vacuum filtration may be -0.05-0.15 MPa, specifically -0.1 MPa.

[0032] The use of the above-mentioned visible light responsive photocatalytic material and the membrane-loaded visible light responsive photocatalytic material as a visible light responsive photocatalyst in the photocatalytic degradation of new pollutants in water also falls within the scope of protection of the present invention.

[0033] Specifically, the new pollutants include diethyltoluamide (DEET), fluoroquinolone drugs, and pathogenic bacteria.

[0034] The fluoroquinolone drugs include but are not limited to ciprofloxacin (CIP), norfloxacin (NOR), and ofloxacin (OFL);

[0035] The pathogenic bacteria include bacteriophages.

[0036] The new material developed by the present invention is responsive to visible light and can use sunlight, a clean energy source, for photocatalysis. The new pollutants involved mainly include DEET, fluoroquinolone drugs and pathogenic bacteria (MS2 bacteriophage). DEET and fluoroquinolone antibiotics are often detected in water environments, and MS2 bacteriophage is similar in size, structure and surface properties to other water-borne viruses, and is representative, so it was selected as a model virus in this patent. This patent introduces nano-zero-valent iron (nZVI) on the basis of graphene oxide-modified carbon-doped g-C3N4 material (GCN-A) for further modification and optimization, thereby improving the efficiency of photogenerated electron-hole separation and thus enhancing its photocatalytic performance; at the same time, the photocatalytic material is attached to the membrane to form a photocatalytic film, so that the new material can be used in the fields of water environment remediation and water treatment engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 (a) is the SEM and TEM images of GCN-A prepared in Example 1 of the present invention, (b) is the SEM and TEM images of IGCN-A, and (c) is the SEM and TEM images of nZVI, among which the upper right corner is the corresponding TEM image.

[0038] Figure 2 (a) is the adsorption-desorption isotherm of the g-C3N4 modified material of the present invention, and (b) is the pore size distribution of the g-C3N4 modified material.

[0039] Figure 3 (a) is the UV-visible diffuse reflectance spectrum of the modified material of the present invention, and (b) is the band gap width.

[0040] Figure 4 This is a diagram showing the photocatalytic degradation of phenol (t=60 min) by the nZVI modified series materials in Example 1 of the present invention.

[0041] Figure 5 (a) is a sample picture of IGCN-AL prepared in Example 3 of the present invention, and (b) and (c) are SEM pictures.

[0042] Figure 6 (a) is the degradation rate of ofloxacin by IGCN-A of the present invention, (b) is the degradation rate of norfloxacin, (c) is the degradation rate of ciprofloxacin, (d) is the degradation rate of DEET, and (e) is the inactivation rate of MS2 phage.

[0043] Figure 7 (a) is the degradation rate of ofloxacin by IGCN-AL prepared in Example 3 of the present invention, (b) is the degradation rate of norfloxacin, (c) is the degradation rate of ciprofloxacin, and (d) is the inactivation rate of MS2 phage.

[0044] Figure 8 It is the degradation rate / inactivation rate of GCN-A in the comparative example of the present invention to ofloxacin (60 min), norfloxacin (60 min), ciprofloxacin (60 min), DEET (120 min), and MS2 phage (120 min). DETAILED DESCRIPTION

[0045] The present invention will be further described in detail below in conjunction with specific embodiments. The examples provided are only for illustrating the present invention and are not intended to limit the scope of the present invention. The examples provided below can serve as a guide for further improvements by those skilled in the art and are not intended to limit the present invention in any way.

[0046] Unless otherwise specified, the experimental methods in the following examples are conventional methods and were performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials and reagents used in the following examples, unless otherwise specified, were all commercially available.

[0047] Example 1. Preparation and optimization of IGCN-A

[0048] 1.1 Reagents and Materials

[0049] Phosphate buffered saline (PBS, 7.2-7.4, 0.01 mol / L) was purchased from Beijing Solaibao Technology Co., Ltd.; nutrient broth, nutrient agar, and agar powder were all purchased from Beijing Aoboxing Biotechnology Co., Ltd.; anhydrous ethanol (99.5%), melamine (99.0%), cyanuric acid (98.0%), barbituric acid (99.0%), phenol (99.5%), ammonium chloride (99.5%), ammonia (25-28%), 4-aminoantipyrine (98%), potassium ferricyanide (99.5%), methanol (HPLC grade , 99.9%), formic acid (HPLC grade, 99%), and acetonitrile (HPLC grade, 99.9%) were purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; graphene oxide (GO) solution, specification (5 mg / mL), was purchased from Nanjing Xianfeng Nanotechnology Co., Ltd.; nano zero-valent iron (nZVI) was purchased from Shanghai Chaowei Nanomaterials Co., Ltd.; norfloxacin (HPLC grade, 99%), ofloxacin (HPLC grade, ≥99%), and ciprofloxacin (HPLC grade, ≥98%) were purchased from Shanghai Yuanye Biotechnology Co., Ltd.; DEET (C 12 H17 NO) was purchased from TCI, Japan. Cellulose acetate membranes (50 mm diameter, 0.45 μm pore size) were purchased from Shanghai Xingya Purification Materials Factory. Bacteriophage MS2 and host E. coli 285 were obtained from Renmin University of China. All chemicals were used in experiments without further purification.

[0050] 1.2 Preparation and modification of photocatalytic materials

[0051] For a new photocatalyst GCN-A that has been developed in the laboratory (see Example 1 of invention patent 202010081377.X for details), nano-zero-valent iron (nZVI) was introduced for modification and optimization (n% IGCN, where n is the mass percentage of nZVI and GCN-A, abbreviated as: n% IGCN). To prevent the oxidation failure of nZVI, the n% IGCN samples in this experiment were all freshly prepared and used. The specific steps are as follows: At 25°C, a certain mass of GCN-A and nZVI were weighed and dispersed in 10mL of high-purity water (high-purity water was previously bubbled with N2) to prepare a series of n% IGCN stock solutions (the concentration of the photocatalyst in the stock solution was 0.05g / mL) (n was 0 / 5 / 7.5 / 10 / 12.5 / 15, respectively). Before the experiment, the n% IGCN stock solution was ultrasonically treated for 1 minute (KQ-300DE, 60kHz) for uniform dispersion. The obtained material was named IGCN.

[0052] 1.3 Characterization of photocatalytic materials

[0053] The micromorphology of the catalytic material was observed using a field emission scanning electron microscope (FE-SEM, Sigma 300, Germany) equipped with an energy dispersive X-ray spectrometer (EDS) and a high-resolution transmission electron microscope (TEM, JEM-2100, Japan). The specific surface area and porosity analyzer (NOVA-2000e, USA) was used to measure the specific surface area of ​​the sample at 300°C for 12 hours and at 77K, and the pore structure was calculated. The optical properties of the material were analyzed using ultraviolet-visible diffuse reflectance spectroscopy (DRS, UV-3600, Japan) with BaSO4 as the background value. The band gap (E g ) is calculated as follows: the diffuse reflectance of the sample is calculated by formula 2-1, and then the diffuse reflection absorption coefficient is calculated according to the Kubelka-Munk function, as shown in formula 2-2. Using the Tauc plot method, as shown in formula 2-3, (αhυ) 1 / n With hυ as the ordinate and hυ as the abscissa, draw a tangent to the most linear part of the curve and intersect it with the abscissa. The intercept is the bandgap width of the material (E g ). The band gap can be converted into an optical absorption band edge by

[0054] Calculated using formula 2-4.

[0055]

[0056]

[0057]

[0058]

[0059] The surface morphology of the samples was characterized by SEM and TEM. Figure 1 As shown in (a), GCN-A presents a wrinkled and fluffy structure. After doping nZVI on the basis of GCN-A, it is observed that in the GCN-A modified material, nZVI spherical particles are more evenly distributed on the GCN-A sheet, showing slight agglomeration, as shown in Figure 2. Figure 1 As shown in (b), the emergence of this structure can better separate the photogenerated electrons and holes and transport them to the surface of the photocatalyst, thereby achieving the purpose of improving the photocatalytic performance.

[0060] The specific surface area and pore distribution of the samples were determined and analyzed by N2 adsorption-desorption isotherm method.

[0061] Depend on Figure 2 In (a), it can be seen that g-C3N4 and IGCN-A both exhibit type IV isotherm curves, indicating that the three materials contain mesoporous structures. Figure 2 As shown in (b), the specific surface area and total pore volume of IGCN-A are lower than those of g-C3N4. This may be due to the small size of nZVI particles, which block some channels of the material, resulting in a decrease in the specific surface area and total pore volume of IGCN-A. However, judging from the degradation ability of phenol, the enhanced photocatalytic activity of the modified material has no direct relationship with the specific surface area.

[0062] The light absorption characteristics of the material were studied using UV-visible diffuse reflectance spectroscopy (DRS) to characterize the catalytic material's ability to utilize visible light. Figure 3 In (a), it can be seen that both g-C3N4 and IGCN-A have visible light response capabilities, and the red shift increases, with the light absorption edges at 460nm and 599nm respectively. Figure 3 As shown in (b), the band gaps of g-C3N4 and IGCN-A are 2.70 eV and 2.07 eV, respectively. The narrowing of the band gap indicates that the visible light utilization efficiency of the modified materials has been improved.

[0063] 1.4 Material doping ratio screening

[0064] The photocatalytic activity of the IGCN series of materials was evaluated using phenol as the target pollutant. The specific method was as follows: First, a certain amount of phenol stock solution was added to a jacketed beaker, and the pH of the system was adjusted to 7.0±0.2. Then, 10 mL of PBS buffer was added, and the mixture was diluted to 100 mL with high-purity water, resulting in a phenol concentration of 10 mg / L. After adding 2 mL of 0.05 g / mL photocatalytic stock solution to bring the IGCN-A concentration in the reaction system to 1 g / L, a magnetic stirrer was set at 500 rpm and stirred in the dark for 30 minutes to achieve adsorption-desorption equilibrium. The xenon lamp was then turned on, and a certain volume of water sample was collected at set intervals. After passing through a 0.22 μm filter, the sample was stored in a centrifuge tube, wrapped in tin foil, and stored in a refrigerator at 4°C until testing. Phenol concentration was determined using the 4-aminoantipyrine spectrophotometric method (HJ 503-2009). The resulting catalyst with the optimal doping level was named IGCN-A.

[0065] The photocatalytic activity of the materials was evaluated using phenol as the target pollutant, e.g. Figure 4 As shown in Figure 2, with increasing nZVI doping levels, the phenol degradation performance of the n% IGCN series of materials under visible light initially increases and then decreases. 10% IGCN exhibits the best photocatalytic performance, achieving a phenol degradation rate of 86%. Therefore, 10% IGCN was selected as the subsequent loading material on the membrane and designated IGCN-A.

[0066] Example 2: Preparation and characterization of photocatalytic films

[0067] 2.1 Preparation method of IGCN-A photocatalytic film

[0068] A 0.5 mg / mL suspension of IGCN-A catalyst was prepared. 20 mL was vacuum filtered onto a cellulose acetate membrane at -0.1 MPa, resulting in a 10 mg photocatalytic layer. The membrane was then exposed to air at ambient temperature and dried. This membrane was designated IGCN-AL.

[0069] After the prepared photocatalytic film is dried, Figure 5 As shown in (a), the membrane surface is smooth and has a certain mechanical strength, the catalyst loading is stable and not easy to fall off.

[0070] 2.2 Characterization of IGCN-AL

[0071] The surface morphology of the materials was observed using a JEOL JSM-7900 cold-field field emission scanning electron microscope. After the materials were completely dry, they were gold-sprayed using a JEOL JFC-1600 gold-spraying instrument to increase the material's conductivity and enhance imaging clarity. Before observation, graphite glue was affixed to the stage, and the test object was attached to the graphite glue. Any part of the test object not adhering to the graphite glue was blown away with an earbud. Finally, the stage was placed in the sample chamber, and observation was performed at an accelerating voltage of 10 kV.

[0072] The results are as follows Figure 5 As shown in (b) and (c), after the material is loaded on the membrane, the material still maintains an irregular layered two-dimensional thin sheet structure with wrinkled edges and smooth surfaces, and the loading does not cause any changes in the morphology.

[0073] Example 3: Removal of new pollutants in water by IGCN-A / AL

[0074] 3.1 Photocatalytic degradation of antibiotics in water by IGCN-A / AL

[0075] 3.1.1 Photocatalytic degradation of antibiotics experiment

[0076] The photocatalytic reaction apparatus used a 66921 direct-type scientific-grade arc lamp housing manufactured by Newport (USA), equipped with a 1000W ozone-free mercury-xenon arc lamp (6295NS, Newport). A filter was used to filter out wavelengths below 400nm to simulate sunlight for photocatalytic experiments. The reaction vessel was a 300mL jacketed beaker. The light source was cooled by an exhaust fan. A liquid filter (6213NS) was connected to a circulating water system (DLSB 5-20, Gongyi Yuhua Technology Co., Ltd.) to absorb heat during the reaction. The 300mL beaker was connected to the circulating water system to maintain a constant reaction temperature of 25°C. A magnetic stirring device (colorsquid, IKA, Germany) was also provided. The measured irradiance intensity for wavelengths above 400nm was 220.3mW·cm -2 .

[0077] First, add a certain amount of antibiotic stock solution to the jacketed beaker, adjust the pH of the system to 7.0±0.2, then add 10mL of PBS, and then dilute to 100mL with high-purity water to make the antibiotic concentration 10mg / L. After adding 2mL of 0.05g / mL photocatalytic stock solution to make the IGCN-A concentration in the reaction system 1g / L, set the magnetic stirrer speed to 500r / min, and stir in the dark for 20min to reach adsorption-desorption equilibrium. Then turn on the xenon lamp, take a certain volume of water sample every 10min, filter it through a 0.22μm filter membrane, store it in a centrifuge tube, wrap it with tin foil and store it in a refrigerator at 4℃ for testing.

[0078] The photocatalytic degradation of antibiotics by IGCN-AL was conducted using an XPA-7 photochemical reactor (1000W xenon lamp, λ>400nm) manufactured by Nanjing Xujiang Electromechanical Factory, simulating visible light. Water samples were collected every 10 minutes for the first hour and every hour thereafter. The samples were filtered through a 0.22μm filter, stored in centrifuge tubes, wrapped in tinfoil, and stored in a refrigerator at 4°C until testing.

[0079] 3.1.2 Determination of antibiotic concentration

[0080] The concentrations of ciprofloxacin (CIP), norfloxacin (NOR), and ofloxacin (OFL) were analyzed using an Agilent 1260 Infinity II High Performance Liquid Chromatography (HPLC) system equipped with a Venusil MP C18 reversed-phase column (4.6 mm × 250 mm × 5 μm) from Agilent Technologies. Water samples were filtered through a 0.22 μm membrane and then transferred to a 2 mL brown liquid phase vial. The liquid phase analysis parameters for OFL, NOR, and CIP are shown in Table 1.

[0081] Table 1 Liquid phase detection parameters of OFL, NOR and CIP

[0082]

[0083]

[0084] Under visible light irradiation, the photocatalytic oxidation effect of IGCN-A on OFL, NOR and CIP changes with time as shown in the following curves: Figure 6 As shown in (a), (b), and (c), the initial antibiotic concentration was 10 mg / L. As the photocatalytic reaction progressed, the concentrations of the different antibiotics showed a steady downward trend. At 60 minutes, the degradation rates of all three fluoroquinolone antibiotics exceeded 80%, with IGCN-A achieving the highest degradation efficiency for NOR, reaching 91.70%. The degradation rates of OFL and CIP were 82.73% and 88.94%, respectively.

[0085] Under visible light irradiation, the photocatalytic oxidation effect of IGCN-AL on OFL, NOR and CIP changes with time as shown below: Figure 7(a), (b), and (c). Degradation efficiency was most significant in the first 3 hours, reaching 89.67%, 92.39%, and 88.15%, respectively. After 8 hours of illumination, the degradation rates of the three antibiotics were all above 90%, reaching 91.41%, 95.69%, and 95.34%, respectively. Compared to light irradiation, antibiotic degradation was slow, and after 8 hours of illumination, the degradation rates were all below 40%.

[0086] 3.2 Photocatalytic degradation of DEET in water by IGCN-A

[0087] 3.2.1 Photocatalytic degradation of DEET

[0088] The prepared IGCN-A was used to perform visible light photocatalytic degradation of DEET. The equipment used was the same as that of the IGCN-A group in 3.1.1. 2 mL of 0.05 g / mL photocatalytic stock solution was added to make the IGCN-A concentration in the reaction system 1 g / L. DEET was diluted with water to adjust the pH (7.0 ± 0.3) and 1 mL of phosphate buffer solution was added to maintain a stable pH. The rotor was stirred at 450 r / min and the system temperature was maintained at 25 ° C. The reaction was stirred in the dark for 20 minutes and the illumination time was 120 minutes. Samples were taken every 10 minutes, and the sample volume was 3 mL each time. After passing through a 0.22 μm filter membrane, it was transferred to a 2 mL brown sample bottle for subsequent concentration analysis.

[0089] 3.2.2 Determination of DEET concentration

[0090] The concentration of DEET was analyzed using a LC-20AD high performance liquid chromatograph (HPLC) produced by Shimadzu Corporation of Japan using a Venusil MP C18(2) 5μm column (4.6×250mm). The water sample was filtered through a 0.22μm filter membrane and transferred to a 2mL brown bottle. High-purity water (pH adjusted with 1% formic acid) and methanol were used as the mobile phase in a volume ratio of 20:80. The flow rate was 1mL / min, the injection volume was set to 20μL, a UV detector was used, the detection wavelength was 229nm, and the column box temperature was set to 40℃.

[0091] like Figure 6 As shown in (d), the initial DEET concentration is 0.5 mg / L. As the photocatalytic reaction progresses, the DEET concentration shows a steady downward trend. The reaction has degraded to below the detection limit at 120 minutes.

[0092] 3.3 Photocatalytic inactivation of MS2 bacteriophage in water by IGCN-A / AL

[0093] 3.3.1 Culture of bacteriophage MS2

[0094] Dissolve 18g of nutrient broth powder in a conical flask filled with 1000mL of high-purity water, seal it with a sealing film with a breathing hole, and place it in a high-temperature and high-pressure sterilizer to sterilize at 121°C for 30 minutes. After cooling, transfer 150mL of nutrient broth to the sterilized conical flask, use an inoculation loop to pick up E. coli colonies into the nutrient broth and stir several times. Then seal the conical flask and place it in an air bath constant temperature shaking incubator, and incubate it at 37°C at 150r / min for 13 hours. Prepare a host E. coli suspension (the initial concentration of the bacterial suspension is about 10 9 CFU / mL), 1 mL of phage concentrate was added to the Escherichia coli suspension cultured for 13 h, and then cultured in a 37 ° C environment for 24 h, and then centrifuged at 10000 r / min using a centrifuge. The upper layer after centrifugation was filtered with a 0.22 μm filter membrane to obtain a concentrated solution (the concentration of the phage concentrate was about 10 9 PFU / mL) were stored in a laboratory refrigerator at 4°C.

[0095] 3.3.2 MS2 Detection and Counting

[0096] The phage titer was determined using a double-layer agar plate method. Nutrient agar sterilized at 121°C for 30 minutes was poured into a culture dish and allowed to cool and solidify. The irradiated sample was plated at 10 n Dilution: Place 1 mL of the diluted sample in a sterile test tube, add 0.2 mL of the host suspension, and add approximately 5 mL of the melted upper culture medium (nutrient broth: agar = 2:1) at approximately 50°C to each test tube, shake well, and immediately pour it onto the lower culture medium and spread it evenly. Place it on a horizontal surface to solidify, with three replicates for each sample. Place the solidified culture dish upside down in an incubator maintained at 37°C. After 5 hours, count the phages on the plate, and one plate unit (PFU) is counted as one infectious virus.

[0097] 3.3.3 Photocatalytic inactivation of MS2

[0098] The prepared IGCN-A was used to perform visible light photocatalytic degradation of MS2. The equipment used was the same as that of the IGCN-A group in 3.1.1. The operation steps were as follows: the phage suspension was diluted with sterile water to 2×10 8The reaction suspension was prepared at a volume of 80 mL. 1.6 mL of 0.05 g / mL photocatalytic stock solution was then added to the jacketed beaker to bring the IGCN-A concentration to 1 g / L. The magnetic stirrer was turned on at 500 rpm, the circulating water pump was turned on, and the reaction temperature was controlled at 25°C. The reaction was stirred in the dark for 30 minutes to achieve adsorption-desorption equilibrium. A 2-hour light irradiation test was then performed, with samples taken every 10 minutes and tested after passing through a 0.22 μm filter.

[0099] The preparation for the IGCN-AL inactivation experiment against MS2 bacteriophage is similar to that for IGCN-A, using the same apparatus as for the IGCN-AL group in 3.1.1. Completely immerse the prepared IGCN-AL photocatalytic membrane in the MS2 suspension, with the catalyst-loaded membrane facing the light source. Without stirring, turn on the circulating water pump and maintain the reaction temperature at 25°C. Initially, incubate the reaction in the dark for 30 minutes to achieve adsorption-desorption equilibrium. Then, perform an 8-hour light irradiation test, sampling every hour. The samples are filtered through a 0.22 μm filter and their potency is determined.

[0100] like Figure 6 As shown in (e), the initial concentration of MS2 is 2×10 8 PFU / mL. Under visible light irradiation, the inactivation of MS2 by IGCN-A proceeded with the photocatalytic reaction. After 2 h of reaction, the amount of MS2 was below the detection limit and almost all of it was inactivated.

[0101] like Figure 7 As shown in (d), after 8 h of illumination, the inactivation rate of MS2 by IGCN-AL was 1.96 log, which was lower than that of IGCN-A. This may be because it was loaded on the membrane, which reduced the contact area between the catalytic material and MS2.

[0102] Study on the removal effect of new pollutants by comparative example and GCN-A

[0103] The removal effect of GCN-A before nZVI modification on several selected new pollutants was studied. The specific operation method was the same as in Example 3, and the concentration of GCN-A in the reaction system was 1g / L. The results are shown in Figure 3. Figure 8 As shown in the figure, after 60 minutes of visible light irradiation, the degradation rates of OFL, NOR and CIP by GCN-A were 79.14%, 79.08% and 76.50%, respectively. After 2 hours of visible light irradiation, the degradation rate of DEET by GCN-A was 93%. After 2 hours of visible light irradiation, the inactivation rate of MS2 was 2.35 log.

[0104] This invention modifies carbon-doped g-C3N4 by introducing nano-zero-valent iron and graphene oxide to synthesize a ternary photocatalyst that enhances the g-C3N4's ability to separate photogenerated charge carriers, thereby boosting its photocatalytic capacity. The supported catalyst, IGCN-AL, is successfully attached to the surface of a cellulose acetate membrane without the need for a crosslinker, effectively improving the catalyst's recovery and recycling capabilities. Under sunlight, it effectively removes new pollutants from water, utilizing sunlight as a clean energy source while effectively removing toxic, difficult-to-biodegrade new pollutants from water.

[0105] The present invention has been described in detail above. For those skilled in the art, without departing from the purpose and scope of the present invention, and without the need to carry out unnecessary experimental conditions, the present invention can be implemented in a wide range under equivalent parameters, concentrations and conditions. Although the present invention provides specific embodiments, it should be understood that further improvements can be made to the present invention. In short, according to the principles of the present invention, this application is intended to include any changes, uses or improvements to the present invention, including changes that depart from the disclosed scope in this application and are made using conventional techniques known in the art.

Claims

1. Use of a visible light responsive photocatalytic material as a visible light responsive photocatalyst for photocatalytic degradation of bacteriophages in water, characterized by: The visible light responsive photocatalytic material is prepared by introducing nano-zero-valent iron into a carbon-doped g-C3N4 material modified with graphene oxide; The visible light responsive photocatalytic material is expressed as n% IGCN, i.e., nZVI / GCN-A, wherein nZVI represents nano-zero-valent iron, GCN-A represents carbon-doped g-C3N4 material modified with graphene oxide, and n% represents the mass percentage of nZVI and GCN-A, with n=7.5-12.

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2. The use according to claim 1, characterized in that: The graphene oxide modified carbon-doped g-C3N4 material is prepared by the following method: 1) Melamine, cyanuric acid, barbituric acid, and GO dispersion are used as precursors, and an anhydrous organic solvent is added thereto to form a suspension; 2) subjecting the suspension to ultrasonic treatment and stirring; 3) Drying the stirred suspension to obtain an off-white solid; 4) The obtained off-white solid is calcined, and the solid product is collected after cooling to obtain a graphene oxide-modified carbon-doped g-C3N4 material.

3. The use according to claim 1 or 2, characterized in that: The method for preparing the visible light responsive photocatalytic material comprises the following steps: first, nitrogen is introduced into water to remove dissolved oxygen in the water; then, carbon-doped g-C3N4 material GCN-A modified with graphene oxide and nano-zero-valent iron nZVI are dispersed in the water; and then ultrasonic treatment is performed to obtain the visible light responsive photocatalytic material.

4. Use of a membrane-supported visible light-responsive photocatalytic material as a visible light-responsive photocatalyst for photocatalytic degradation of bacteriophages in water, characterized by: The membrane-supported visible light responsive photocatalytic material is prepared by loading the visible light responsive photocatalytic material onto the membrane; The visible light responsive photocatalytic material is prepared by introducing nano-zero-valent iron into a carbon-doped g-C3N4 material modified with graphene oxide; The visible light responsive photocatalytic material is expressed as n% IGCN, i.e., nZVI / GCN-A, wherein nZVI represents nano-zero-valent iron, GCN-A represents carbon-doped g-C3N4 material modified with graphene oxide, and n% represents the mass percentage of nZVI and GCN-A, with n=7.5-12.

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5. The use according to claim 4, characterized in that: The membrane is a cellulose acetate membrane.

6. The use according to claim 4 or 5, characterized in that: The method for producing a film-supported visible light-responsive photocatalytic material comprises the following steps: 1) Melamine, cyanuric acid, barbituric acid, and GO dispersion are used as precursors, and an anhydrous organic solvent is added thereto to form a suspension; 2) ultrasonically treating the suspension and stirring; 3) Drying the stirred suspension to obtain an off-white solid; 4) calcining the obtained off-white solid, and collecting the solid product after cooling to obtain a graphene oxide-modified carbon-doped g-C3N4 material; 5) Nitrogen is first introduced into the water to remove dissolved oxygen in the water, and then the carbon-doped g-C3N4 material GCN-A modified with graphene oxide and nano-zero-valent iron nZVI are dispersed in the water and ultrasonically treated to obtain a catalyst suspension; 6) The obtained catalyst suspension is vacuum filtered on a membrane to obtain the catalyst.

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